"Phantom" overwrite with dd on sda*? Post: 302921530

Sponsored Content

Top Forums UNIX for Advanced & Expert Users "Phantom" overwrite with dd on sda*? Post 302921530 by Don Cragun on Friday 17th of October 2014 10:21:31 PM

10-17-2014

Registered User

Quote:

Originally Posted by LinQ

Thanks again, Don.

So, let me get this straight.

We essentially created a file called sda* in a /dev/ folder on the flash drive, and filled it with zeros until there was no more space at the inn (per usual dd practice).

If so, that could explain the constant 1GB output.

However, I saw this over on stackexchange regarding an (unfortunate) use of /dev/sda*( partition - Ignorantly dd'd /dev/sda* - Unix & Linux Stack Exchange )

Realizing the limitation which dd has with respect to output per invocation, how could this have happened?

Thanks again --

Not essentially; exactly. Use the command:

Code:

ls -l /dev/sda*

and you'll see the device files that already existed and the regular file named /dev/sda* that you just created with dd with size 1027362816.

Let me see if I understand this correctly. You looked at a website that never showed what dd command was used, but had a description that started with the paragraph:

Quote:

I was trying to write an iso to a flash drive. I mistakenly thought that all /dev/sda* are flash drives attached to the system. I wasn't sure how to figure out which was which, so I just unplugged my flash drives and overwrote them all. In retrospect.... this was unbelievably dumb.

and went on to ask if it was possible to recover his system since it would no longer boot. And you decided to try to duplicate what the person who asked that question described as unbelievably dumb behavior.

Instead of us telling you how you can wipe out all of the data on all of your disk drives by copying /dev/zero to them, why don't you tell us what you're really trying to do?

Don Cragun

View Public Profile for Don Cragun

Find all posts by Don Cragun

9 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Explain the line "mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'`"

Hi Friends, Can any of you explain me about the below line of code? mn_code=`env|grep "..mn"|awk -F"=" '{print $2}'` Im not able to understand, what exactly it is doing :confused: Any help would be useful for me. Lokesha

2. UNIX for Advanced & Expert Users

"Phantom character" in Socket (RESOLVED)

Hi everyone: I have built a tcl script, this script communicate with an ADA program trough a socket, sending binary data, the sender proc is this one: The code where im sending info is here: proc p_send_data { DATA } { global connection puts "Sending trough $connection..." #...

3. Shell Programming and Scripting

cat $como_file | awk /^~/'{print $1","$2","$3","$4}' | sed -e 's/~//g'

hi All, cat file_name | awk /^~/'{print $1","$2","$3","$4}' | sed -e 's/~//g' Can this be done by using sed or awk alone

4. Shell Programming and Scripting

awk command to replace ";" with "|" and ""|" at diferent places in line of file

Hi, I have line in input file as below: 3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL My expected output for line in the file must be : "1-Radon1-cMOC_deg"|"LDIndex"|"3G_CENTRAL|INDONESIA_(M)_TELKOMSEL"|LAST|"SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL" Can someone...

5. Shell Programming and Scripting

how to use "cut" or "awk" or "sed" to remove a string

logs: "/home/abc/public_html/index.php" "/home/abc/public_html/index.php" "/home/xyz/public_html/index.php" "/home/xyz/public_html/index.php" "/home/xyz/public_html/index.php" how to use "cut" or "awk" or "sed" to get the following result: abc abc xyz xyz xyz

6. Solaris

The slices "usr", "opt", "tmp" disappeared!!! Help please.

The system don't boot. on the screen appears following: press enter to maintenance (or type CTRL-D to continue)...I checked with format command. ... the slices "0-root","1-swap","2-backup" exist. ...the slises "3-var","6-usr" -unassigned. :(

7. UNIX for Dummies Questions & Answers

Using "mailx" command to read "to" and "cc" email addreses from input file

How to use "mailx" command to do e-mail reading the input file containing email address, where column 1 has name and column 2 containing �To� e-mail address and column 3 contains �cc� e-mail address to include with same email. Sample input file, email.txt Below is an sample code where...

8. Shell Programming and Scripting

Bash script - Print an ascii file using specific font "Latin Modern Mono 12" "regular" "9"

Hello. System : opensuse leap 42.3 I have a bash script that build a text file. I would like the last command doing : print_cmd -o page-left=43 -o page-right=22 -o page-top=28 -o page-bottom=43 -o font=LatinModernMono12:regular:9 some_file.txt where : print_cmd ::= some printing...

9. AIX

Apache 2.4 directory cannot display "Last modified" "Size" "Description"

Hi 2 all, i have had AIX 7.2 :/# /usr/IBMAHS/bin/apachectl -v Server version: Apache/2.4.12 (Unix) Server built: May 25 2015 04:58:27 :/#:/# /usr/IBMAHS/bin/apachectl -M Loaded Modules: core_module (static) so_module (static) http_module (static) mpm_worker_module (static) ...

LEARN ABOUT DEBIAN

pvck

PVCK(8) 						      System Manager's Manual							   PVCK(8)

NAME

       pvck - check physical volume metadata

SYNOPSIS

       pvck [-d|--debug] [-h|--help] [-v|--verbose] [--labelsector] PhysicalVolume [PhysicalVolume...]

DESCRIPTION

       pvck checks physical volume LVM metadata for consistency.

OPTIONS

       See lvm for common options.

       --labelsector sector
	      By  default, 4 sectors of PhysicalVolume are scanned for an LVM label, starting at sector 0.  This parameter allows you to specify a
	      different starting sector for the scan and is useful for recovery situations.  For example, suppose the partition table is corrupted
	      or  lost	on  /dev/sda, but you suspect there was an LVM partition at approximately 100 MB.  This area of the disk may be scanned by
	      using the --labelsector parameter with a value of 204800 (100 * 1024 * 1024 / 512 = 204800):

	      pvck --labelsector 204800 /dev/sda

	      Note that a script can be used with --labelsector to automate the process of finding LVM labels.

SEE ALSO

       lvm(8), pvcreate(8), pvscan(8) vgck(8)

Sistina Software UK					 LVM TOOLS 2.02.95(2) (2012-03-06)						   PVCK(8)